The age newborn pigs are weaned from the sow can vary depending on the production goals and health status of the farm. The standard weaning age in the swine industry is from 14 to 21 days of age as this maximizes production of the sow, which is placed back in the breeding cycle thereby increasing the number of pigs born by the sow per year. Weaning at this age also provides the weanling pig with positive nutrition and fairly optimal health. If the farm has a poor health status, pigs may be weaned earlier, e.g., from 5 to 7 days of age, and moved to an offsite facility having a higher health status to break the disease cycle of the farm.
Weaning at 14 to 21 days of age or earlier has drawbacks. The digestive system of young pigs is designed to accept and absorb nutrients from milk. Feeding milk to newborn pigs is cost prohibitive. Grain and forage feed products suitable for older pigs are problematic for young pigs because their digestive tracts are not capable of efficiently digesting the feed. Digestion difficulties lead to post-weaning lag, a term used to describe the event when young pigs exhibit slow weight gain and low feed intake.
Efforts have been made to develop more tolerable feed products for young pigs. These “starter” diets are high in digestible nutrients. Such diets consist of processed grains (corn, wheat barley, rice, etc.), gelatinized starches, milk products (dried skim milk, dried whey, lactose, dried whey protein concentrate, casein, etc.), sugars (dextrose, glucose, sucrose), fats and oils (lard, grease, vegetable oils, coconut oil, etc.), animal proteins (fish meal, animal blood meal, meat meal, etc.), and refined, extruded soybeans (soy protein isolate, soy protein concentrate). Even with the use of such starter diets, post-weaning lag remains a concern.
To alleviate post-weaning lag, starter diets for newly-weaned pigs have been supplemented with dried animal plasma. Spray-dried porcine plasma has been used as a feed supplement to increase the weight gain of early-weaned pigs. (Coffey, R. D. et al, 1995. The impact of environmental and antimicrobial agents on the growth response of early-weaned pigs to spray-dried porcine plasma, J. Anim. Sci., 73, 2532-2539, incorporated herein by reference). Weight gain increase in early-weaned pigs fed with a supplement of spray-dried bovine, porcine, or avian blood meal has been found. (Kats, L. J. et al, 1994. The effects of spray-dried blood meal on growth performance of early-weaned pig, J. Anim. Sci., 72, 2860-2869, incorporated herein by reference).
U.S. Pat. No. 5,575,999 discloses a blended powdered feed supplement comprising animal plasma (e.g., pig or cow plasma) and a microbial fermentation product, primarily amylase.
U.S. Pat. No. 5,785,990 discloses a liquid feed fortifier for preruminant, bovine calves comprising animal plasma and other ingredients (e.g., vitamins, minerals, electrolytes, etc.).
U.S. Pat. No. 6,004,576 discloses a feed supplement of granulated animal plasma (e.g., porcine, bovine, ovine, equine, or avian plasma).
U.S. Pat. No. 6,569,447 discloses a performance-enhancing feed supplement comprising spray-dried porcine plasma and spray-dried hyperimmune egg.
Even with the use of starter diets supplemented with animal plasma, the practice of supplementing feed with subtherapeutic doses of antibiotics to improve feed efficiency and growth is routine. The specific mode of action for enhanced growth is unknown; the improvement in efficiency is due to a more favorable gut microflora.
Subtherapeutic use of antibiotics in diets of farm production animals was first introduced in 1946 when the addition of subtherapeutic levels of antimicrobials was found to enhance growth in poultry. (Moore, P. R., et al., 1946. Use of sulfasuxidine, steptothricin, and streptomycin in nutritional studies with the chick, J. Biol. Chem., 165:437-445, incorporated by reference herein). Today, antimicrobial agents are incorporated in approximately 90% of weanling, 75% grower, and 50% of finishing swine diets. As mentioned above, pigs are typically weaned early (on average at 21 days of age). Because weaning pigs receive immunity through the dam's colostrum, weaning interrupts this process. With an immature immune system, early-weaned pigs are not able to effectively combat bacterial disease until about four months of age. Their diets are usually fortified with antibiotics to prevent disease but also to increase growth and feed efficiency.
Given the widespread subtherapeutic use of antibiotics, consumers of animal products are becoming concerned with the potential for bacterial resistance. The European Union has banned the use of subtherapeutic antibiotics in swine feed. Major food service companies in Europe have gone so far as to develop policies regulating the use of antibiotics in animals they purchase. Consumers and the food service industry in the United States have signaled a desire to move in the same direction. As a result, researchers are striving to find alternatives to antibiotics such as probiotics, competitive exclusion, enzymes, immune modulators, organic acids, minerals, vitamins, conjugated linoleic acids, phospholipids, amino acids, carnitine, carbohydrates, and herbs. (Doyle, E., 2002. Alternative to antibiotic use for growth promotion in animal husbandry; A Review of Scientific Literature, Report NPPC, 98, 162, incorporated herein by reference).
Despite the development of diets supplemented with animal plasma and of alternatives to the subtherapeutic use of antibiotics, the need still exists for feed supplements that increase weight gain, feed intake, and promote gut health so that the use of subtherapeutic antibiotics can be reduced or eliminated.